1. Field
The embodiments discussed herein are directed to data copying and, in particular, to determination of data identity between copy source data and copied data.
2. Description of the Related Art
Telephone networks constructed on the basis of the existing circuit switching technology are being replaced with communication networks of IP (Internet Protocol) packet base on the basis of a packet switching technology. In addition, the backbone transmission networks of layer 2 are also being replaced with an Ethernet (registered trademark) based transmission method, which is low-cost and compatible with the IP packet. Regardless of the low cost of a system (data transmitter) used in the backbone transmission network, fault tolerance and maintainability required of the known transmission technique of SDH/SONET (Synchronous Digital Hierarchy/Synchronous Optical NETwork) are still required for such a system. Japanese Laid-open Patent Publication No. 08-37527 and Japanese Laid-open Patent Publication No. 2005-260742 disclose related arts.
For system maintainability, the Ethernet based packet transmission system may be required to incorporate a monitoring of the content of an output packet e.g., output port mirror or port mirroring. In such a system, an output mirror port may be provided in a card separate from an interface card outputting normal data.